The invention relates to an apparatus for the maintenance of refrigeration equipment, specifically refrigeration equipment including an intermediate circuit.
Refrigeration equipment operating in accordance with the Rankine cyclical process generally comprise a closed circuit for the refrigerant such as may be based on fluorine and hydrocarbons. If the equipment components participating in the cyclical process such as the heat absorber or froster and the equipment for discharging heat such as the compressor and cooling coils are separated from one another in space, it is necessary to convey the refrigerant through respective pipe conduits. Refrigeration equipment on board of aircraft, comprise in addition to the above mentioned first or primary circuit, a second circuit also referred to as an intermediate or secondary circuit located between the cooling component of the system and the remaining refrigeration components of the system. A second refrigerant circulates within this secondary circuit. The second refrigerant may for example consist of a propylene-glycol water mixture. In this type of refrigeration system only the second refrigerant, which does not cause any problems as compared to the refrigerant in the primary system, is caused to circulate through the pipe conduits installed on board between the refrigerating means proper and the remaining components of the system in the kitchen zone.
Due to the just described arrangement of the on-board systems, the following steps are necessary for the maintenance of such systems. First the pipe conduits of the secondary circuit are to be emptied under pressure with the aid of pressurized nitrogen. Second, the pipe conduits must be replenished or refilled with refrigerant. Third, the system must be vented. Due to the described structural arrangement these steps are limited to the secondary circuit.
It is known, that these steps are performed with due regard to prescribed maintenance procedures. However, the performance of these steps is rather uneconomical. For example, the emptying under pressure involves the use of a separate apparatus provided specifically for this purpose. The replenishing or refilling and venting is performed by means of a multi-purpose apparatus which is constructed to also permit maintenance work on the primary circuit. Accordingly, this multi-purpose apparatus is rather expensive in its structure and accordingly it is not suitable for being taken on board for the performance of maintenance work. Besides, this type of apparatus requires two operators. One operator is stationed on board and connects or disconnects the respective couplings at the corresponding interface on board. The other operator handles the multi-purpose apparatus on the ground. Thus, the two operators necessarily require a communication link between each other for example in the form of a ratio link, such as a walkie-talkie. Besides, this multi-purpose apparatus depends on an external power supply because its installed pump is electrically driven.